大兴安岭北段下嘎来奥伊铅锌矿地质、物化探特征及找矿方向

Geological, geochemical and geophysical characteristics and prospecting direction of Xiagalaiaoyi Pb-Zn deposit in the northern section of the Great Xing’an Range

下嘎来奥伊铅锌矿位于黑龙江省西北部,大地构造位置位于额尔古纳地块额木尔山隆起带南缘与大兴安岭火山岩带北缘交切部位的西段。矿体主要产于中酸性浅成侵入岩与新元古界—下寒武统倭勒根群吉祥沟组大理岩接触带,是一个以铁、铅、锌、钼矿为主的矽卡岩型矿床。通过野外工作和室内观察将其成矿期划分为2期5个阶段:(1)矽卡岩期:干矽卡岩阶段、湿矽卡岩阶段(形成富集的磁铁矿)、氧化物阶段(形成少量辉钼矿),(2)石英-硫化物期:早硫化物阶段(形成部分辉钼矿)、晚硫化物阶段(主要形成闪锌矿、方铅矿等铅锌硫化物)。结合成矿地质背景、矿区物化探特征,得出成矿控制因素为:(1)吉祥沟组大理岩及片岩在成矿过程中提供了部分成矿物质,(2)花岗斑岩、花岗闪长岩、细粒花岗岩等中酸性岩体在侵入过程中提供了成矿物质和能量,(3)矿区中部复式褶皱构造及北东向和北西向断裂是区内的主要控矿构造。在GIS平台上开展综合信息成矿预测,共圈出2处找矿预测区,指出了今后的找矿方向。这些认识对矿区及外围找矿工作具有重要的指导意义,为进一步开展深部找矿和相关理论研究提供了重要依据。

The Xiagalaiaoyi Pb-Zn deposit is located in the western segment of the intersecting section of the southern edge of the Ergun block Ermul mountain uplift region and the northern margin of the Great Xing’an Range volcanic belt, northwest of Heilongjiang Province.The ore bodies are mainly Fe, Pb, Zn and Mo and occur in the contact zone between the intermediate acid epithermal intrusive rocks and the marble of Wolegen group jixianggou formation(Neoproterozoic-lower Cambrian).It is a skarn type deposit.In this paper, based on the fieldwork and indoor observation, its metallogenic epoch was divided into 2 periods and 5 stages, which are skarn period:(1) dry skarn stage,(2) wet skarn stage(enriched magnetite),(3) Oxide stage(a small amount of molybdenite),and quartz-sulfide period:(1) early sulfide stage(part of molybdenite);(2) late sulfide stage(sphalerite and galena).Combined with the ore-forming geological background, geochemical and geophysical characteristics of the Xiagalaiaoyi Pb-Zn deposit, the ore-forming controlling factors could be concluded as follows:(1) the marble and schist of the jixianggou formation provide some metallogenic materials during the metallogenic process,(2) granite porphyry, granodiorite, fine-grained granite and other intermediate-acid rocks provide ore-forming materials and energy during the intrusion process,(3) the multiple fold structure in the middle of mining area and the NE and NW directions faults are the main ore-controlling structures.The comprehensive information metallogenic prediction was carried out on the GIS platform, which ringed 2 prospecting prediction areas and pointed out the future prospecting directions.The above research results and understanding will be of great guiding significance to the prospecting in the mining area and its periphery, and provide important evidences for further deep prospecting and related theoretical research.